Recording A Mix

Sorry if this thread's been done a thousand times before. If it has , could somebody just link me to the thread please. But from the very first step...how do you do this? I have decks and a laptop, so where do I take it from there?http://www.htfr.com/more-info/MR300028
I was eyeing up that but is there free software to download and then the necessary cables can just be purchased instead? Basically just absolute guidance about how to do this would be appreciated!
Thanks.